Given the silly fuel prices I was wondering which driving style will
give better MPG and save fuel?

For e.g: If I'm driving at a steady 40mph along a flat road using about 
1/4 throttle in top gear and I approach an incline, to maintain a steady
40mph will it be better on fuel if I change down a gear and use higher 
RPM but less throttle? or is it better on fuel if I remain in a high 
gear but use more throttle and less RPM?

In article , John says...

> Given the silly fuel prices I was wondering which driving style will
> give better MPG and save fuel?
> 
> For e.g: If I'm driving at a steady 40mph along a flat road using about 
> 1/4 throttle in top gear and I approach an incline, to maintain a steady
> 40mph will it be better on fuel if I change down a gear and use higher 
> RPM but less throttle? or is it better on fuel if I remain in a high 
> gear but use more throttle and less RPM? 
> 

What saves more fuel is how you approach traffic lights, roundabouts 
and junctions.

The idea is to approach them and time it so you never actually stop 
rolling. It does mean however that you need to back off a bit further 
back so YOU are controlling when you set off, not the vehicle in front.


-- 
Conor

The child is grown, the dream is gone.
I have become comfortably numb. - Pink Floyd

Conor (conor.turton@gmail.com) gurgled happily, sounding much like they 
were saying :


> What saves more fuel is how you approach traffic lights, roundabouts 
> and junctions.


"The right pedal uses fuel, the middle one wastes it."

Dave Plowman (News) wrote:

	[...]


> It of course depends on the drag of the vehicle and what its fuel
> consumption is at 70 anyway.


On a recent European trip I was getting ~24mpg while averaging ~75mph
(60-90 mostly, not much WOT) which dropped to ~18mpg while averaging
~130mph (90-160 mostly, loads of WOT).  I suspect most of the difference
was fuel used regaining fast cruise after being slowed by traffic rather
than maintaining the higher speed.

I doubt if there is much fuel penalty for me doing 80 rather than 70.

:)



A

John wrote:

> Given the silly fuel prices I was wondering which driving style will
> give better MPG and save fuel?
>
> For e.g: If I'm driving at a steady 40mph along a flat road using about
> 1/4 throttle in top gear and I approach an incline, to maintain a steady
> 40mph will it be better on fuel if I change down a gear and use higher
> RPM but less throttle? or is it better on fuel if I remain in a high
> gear but use more throttle and less RPM?


It would depend on whether the engine would be labouring or not. If you
were driving a non turbo diesel (eg. an old BX frinstance) then you
could get away with it but in a petrol or turbo diesel probably not. If
you treat the accelerator like it's made of glass then you won't go far
wrong. Plus keep the car moving, anticipate where you might need to
stop etc., because it's the changes of speed that use up the fuel more
than a constant speed.

-- 
Malc

> It would depend on whether the engine would be labouring or not. If you
> were driving a non turbo diesel (eg. an old BX frinstance) then you
> could get away with it but in a petrol or turbo diesel probably not. If
> you treat the accelerator like it's made of glass then you won't go far
> wrong. Plus keep the car moving, anticipate where you might need to
> stop etc., because it's the changes of speed that use up the fuel more
> than a constant speed.
>


Also, consider that every time you brake you are effectively using fuel, in 
that you used fuel to get to that speed and now you are throwing that speed 
away. Don't read into this that I don't think you should brake, just that by 
driving in a certain way (not too close behind another vehicle, for example) 
you may reduce the amount of times you have to brake.

Rob Graham

In article <fef6u2-t3b.ln1@florin.fluffy>,
   Alistair J Murray  wrote:

> > It of course depends on the drag of the vehicle and what its fuel
> > consumption is at 70 anyway.

> On a recent European trip I was getting ~24mpg while averaging ~75mph
> (60-90 mostly, not much WOT) which dropped to ~18mpg while averaging
> ~130mph (90-160 mostly, loads of WOT).  I suspect most of the difference
> was fuel used regaining fast cruise after being slowed by traffic rather
> than maintaining the higher speed.

> I doubt if there is much fuel penalty for me doing 80 rather than 70.


Not on my BMW 528 auto either. Setting the cruise control at 75 gives 34
mpg on a reasonably clear motorway over long distances. Nudge it up to 90,
and it drops to 32.

-- 
*He's not dead -  he's electroencephalographically challenged

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

"Alistair J Murray"  wrote in message 
news:fef6u2-t3b.ln1@florin.fluffy...

> Dave Plowman (News) wrote:
>
> [...]
>
>> It of course depends on the drag of the vehicle and what its fuel
>> consumption is at 70 anyway.
>
> On a recent European trip I was getting ~24mpg while averaging ~75mph
> (60-90 mostly, not much WOT) which dropped to ~18mpg while averaging
> ~130mph (90-160 mostly, loads of WOT).  I suspect most of the difference
> was fuel used regaining fast cruise after being slowed by traffic rather
> than maintaining the higher speed.
>
> I doubt if there is much fuel penalty for me doing 80 rather than 70.
>
> :)



Thanks for sharing that with us, git! :)

-- 
The DervMan
www.dervman.com

"John"  wrote in message 
news:3n0pi8F193r1nU1@individual.net...

> Given the silly fuel prices I was wondering which driving style will
> give better MPG and save fuel?
>
> For e.g: If I'm driving at a steady 40mph along a flat road using about 
> 1/4 throttle in top gear and I approach an incline, to maintain a steady
> 40mph will it be better on fuel if I change down a gear and use higher RPM 
> but less throttle? or is it better on fuel if I remain in a high gear but 
> use more throttle and less RPM?



It might - depending on the vehicle and gradient.  The below won't apply to 
your car unless it's an Endura-E Ka, but the idea may well be similar.

I've done quite a bit of work into this with our own Ka.  I've plotted 
relative engine efficiency, as dictated by the throttle and calculated load 
readings, across lots and lots of engine speed.  Trying to compare gear for 
gear is meaningless, but the engine appears to be at its most relaxed 
compared to what it is capable of porducing when cruising between just under 
2,000 rpm to around 2,850 rpm.

The Ecotek valve influenced the chart, almost certainly because it was 
leaking air into the system, which was changing the calculated load figure. 
I'm pleased to report that there was no difference in fuel consumption after 
removing the device so the valve doesn't break the laws of physics as some 
of my fellow Ka peers claim. :)

Check out the graph (nice orangy background, heh, sorry) here:

http://www.dervman.com\dervman\donkeffic.jpg

At 40 indicated in top, our engine is turning over at around 1,850 rpm and 
at 2,330 rpm in fourth.  At 40 GPS-corrected, we have around 2,000 in fourth 
and 2,500 rpm in second.  If I stick to an indicated 40 I should probably 
use fourth... and certainly when I come to a hill.  If my chart has produced 
meaningful data...

That's the $64,000 question though!

-- 
The DervMan
www.dervman.com

DervMan wrote:

> 
> "Alistair J Murray"  wrote in message
> news:fef6u2-t3b.ln1@florin.fluffy...
> > Dave Plowman (News) wrote:
> >
> > [...]
> >
> >> It of course depends on the drag of the vehicle and what its fuel
> >> consumption is at 70 anyway.
> >
> > On a recent European trip I was getting ~24mpg while averaging ~75mph
> > (60-90 mostly, not much WOT) which dropped to ~18mpg while averaging
> > ~130mph (90-160 mostly, loads of WOT).  I suspect most of the difference
> > was fuel used regaining fast cruise after being slowed by traffic rather
> > than maintaining the higher speed.
> >
> > I doubt if there is much fuel penalty for me doing 80 rather than 70.
> >
> > :)
> 
> Thanks for sharing that with us, git! :)


I find that driving below 200mph saves some fuel.

"DervMan"  wrote in
news:x4EQe.7150$B4.1463@newsfe7-win.ntli.net: 

  At 40 GPS-corrected, we have around 2,000

> in fourth and 2,500 rpm in second.

            ^^^^^^^^^^^^^^^^^^^^^^^^

Blimey - that's high gearing for a Ka! With a redline of, say, 6000 rpm, 
that gives you a max speed of 96mph in second! ;-)



-- 
Stuart Sharp

Stu (nobody@home.com) gurgled happily, sounding much like they were saying 
:


>> At 40 GPS-corrected, we have around 2,000
>> in fourth and 2,500 rpm in second.

> Blimey - that's high gearing for a Ka! With a redline of, say, 6000 rpm, 
> that gives you a max speed of 96mph in second! ;-)


Not to mention that third is rather pointless with second and fourth only 
500rpm apart.

"Stu"  wrote in message 
news:Xns96C19DEBA4CEBnobodyhomecom@216.196.109.144...

> "DervMan"  wrote in
> news:x4EQe.7150$B4.1463@newsfe7-win.ntli.net:
>
>  At 40 GPS-corrected, we have around 2,000
>> in fourth and 2,500 rpm in second.
>            ^^^^^^^^^^^^^^^^^^^^^^^^
>
> Blimey - that's high gearing for a Ka! With a redline of, say, 6000 rpm,
> that gives you a max speed of 96mph in second! ;-)



You've never driven a Ka then?  You don't know that it has 600 bhp?

I don't know why I wrote "second" when I meant "fifth" hehehehe. :)

-- 
The DervMan
www.dervman.com

Rob graham  writes

>
>> If
>> you treat the accelerator like it's made of glass then you won't go far
>> wrong. Plus keep the car moving, anticipate where you might need to
>> stop etc., because it's the changes of speed that use up the fuel more
>> than a constant speed.
>>
>
>Also, consider that every time you brake you are effectively using fuel, in
>that you used fuel to get to that speed and now you are throwing that speed
>away. Don't read into this that I don't think you should brake, just that by
>driving in a certain way (not too close behind another vehicle, for example)
>you may reduce the amount of times you have to brake.
>
>Rob Graham
>

These two replies illustrate the way I drive since I got a Mondeo (1.8) 
with the MPG readout.      ;-)

The killer is being stationary at lights etc, and you can sit and watch 
the figure drop at tickover speed.       Driving around town I find it 
worth while getting at least into 4th as soon as possible, which gives 
over 30mpg, and at 30mph in top gear the figure edges up close to 34 mpg 
allowing for a few hold-ups.
-- 
Gordon Harris